Interconnect arrangement with stress-reducing structure and method of fabricating the same

ABSTRACT

A semiconductor device structure and a method of fabricating the same are provided. The semiconductor structure includes a substrate and an interconnection structure formed over the substrate. The interconnection structure includes a first dielectric layer and a first stress-reducing structure formed in the first dielectric layer. The interconnection structure further includes a first conductive feature formed in the first dielectric layer, and the first conductive feature is surrounded by the first stress-reducing structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of copending U.S. patent application Ser. No. 14/162,158, filed on Jan. 23, 2014, which is hereby expressly incorporated by reference into the present application herein.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.

One of the important drivers for increased performance in computers is the higher levels of integration of circuits. This is accomplished by miniaturizing or shrinking device sizes on a given chip. As feature densities in the semiconductor devices increase, the widths of the conductive lines, and the spacing between the conductive lines of back-end of line (BEOL) interconnect structures in the semiconductor devices also need to be scaled down.

However, although existing methods for forming interconnect structures have been generally adequate for their intended purposes, as device scaling-down continues, they have not been entirely satisfactory in all respects.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIGS. 1A-1N are cross-sectional representations of various stages of forming a semiconductor device structure in accordance with some embodiments.

FIG. 2 is a top-view representation of a semiconductor device structure in accordance with some embodiments.

FIGS. 3A-3C are cross-sectional representations of various semiconductor device structures in accordance with various embodiments.

DETAILED DESCRIPTION

The making and using of various embodiments of the disclosure are discussed in detail below. It should be appreciated, however, that the various embodiments can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative, and do not limit the scope of the disclosure.

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of the disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. Moreover, the performance of a first process before a second process in the description that follows may include embodiments in which the second process is performed immediately after the first process, and may also include embodiments in which additional processes may be performed between the first and second processes. Various features may be arbitrarily drawn in different scales for the sake of simplicity and clarity. Furthermore, the formation of a first feature over or on a second feature in the description may include embodiments in which the first and second features are formed in direct or indirect contact.

Some variations of the embodiments are described. Throughout the various views and illustrative embodiments, like reference numbers are used to designate like elements. It is understood that additional operations can be provided before, during, and after the method, and some of the operations described can be replaced or eliminated for other embodiments of the method.

Embodiments of a semiconductor device structure and a method for fabricating the same are provided in accordance with some embodiments of the disclosure. The semiconductor device structure may include an interconnect structure having a conductive feature formed in a dielectric layer.

FIGS. 1A-1N illustrate cross-sectional representations of various stages of forming a semiconductor device structure 100 in accordance with some embodiments. As shown in FIG. 1A, a substrate 102 is provided in accordance with some embodiments. Substrate 102 may be a semiconductor wafer such as a silicon wafer. Alternatively or additionally, substrate 102 may include elementary semiconductor materials, compound semiconductor materials, and/or alloy semiconductor materials. Examples of the elementary semiconductor materials may be, but are not limited to, crystal silicon, polycrystalline silicon, amorphous silicon, germanium, and/or diamond. Examples of the compound semiconductor materials may be, but are not limited to, silicon carbide, gallium arsenic, gallium phosphide, indium phosphide, indium arsenide, and/or indium antimonide. Examples of the alloy semiconductor materials may be, but are not limited to, SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and/or GaInAsP.

Substrate 102 includes device region 106, as shown in FIG. 1A in accordance with some embodiments. Device region 106 may have various device elements. Examples of device elements may include, but are not limited to, transistors, diodes, and/or other applicable elements. Examples of the transistors may include, but are not limited to, metal oxide semiconductor field effect transistors (MOSFET), complementary metal oxide semiconductor (CMOS) transistors, bipolar junction transistors (BJT), high voltage transistors, high frequency transistors, p-channel and/or n-channel field effect transistors (PFETs/NFETs), or the like. Various processes are performed to form the device elements, such as deposition, etching, implantation, photolithography, annealing, and/or other applicable processes. In some embodiments, device region 106 is formed in substrate 102 in a front-end-of-line (FEOL) process.

A dielectric layer 110 is formed over substrate 102, as shown in FIG. 1A in accordance with some embodiments. In some embodiments, dielectric layer 110 is an inter-metal dielectric (IMD) layer. Dielectric layer 110 may include multilayers made of multiple dielectric materials, such as a low dielectric constant or an extreme low dielectric constant (ELK) material. Examples of the dielectric materials may include, but are not limited to, oxide, SiO₂, borophosphosilicate glass (BPSG), tetraethyl orthosilicate (TEOS), spin on glass (SOG), undoped silicate glass (USG), fluorinated silicate glass (FSG), high-density plasma (HDP) oxide, or plasma-enhanced TEOS (PETEOS). Dielectric layer 110 may be formed by chemical vapor deposition (CVD), physical vapor deposition, (PVD), atomic layer deposition (ALD), spin-on coating, or other applicable processes.

A first photoresist layer 113 is formed over dielectric layer 110, and first photoresist layer 113 includes one or more opening 114, as shown in FIG. 1B in accordance with some embodiments. The shape of opening 114 may be adjusted as required. In some embodiments, opening 114 has a shape that is an enclosed or non-enclosed circle, rectangle, ellipse, square, or polygon, when viewed from a top view or above (not shown). In some embodiments, opening 114 includes an n-shaped structure, T-shaped structure, bar-shaped structure, and/or a linear structure, when viewed from a top view or above (not shown).

After first photoresist layer 113 is formed, an etching process 116 is performed to etch dielectric layer 110 through opening 114, as shown in FIG. 1C in accordance with some embodiments. A stress-reducing structure trench 118 is formed in dielectric layer 110 by etching process 116. Etching process 116 may be a wet etching process or a dry etching process.

After etching process 116 is performed, first photoresist layer 113 is removed, and a stress-relieving material 120 is provided to fill in stress-reducing structure trench 118, as shown in FIG. 1D in accordance with some embodiments. Stress-relieving material 120 is deposited and forms a stress-relieving or stress-reducing guard ring or structure to block or prevent stress forces from acting on the conductive feature formed in sequential processes.

In some embodiment, stress-relieving material 120 is a material different from the material used to form dielectric layer 110. Therefore, stress-relieving material 120 is capable of stopping stress caused by dielectric layer 110 from reaching conductive feature 108. In some embodiments, dielectric layer 110 is made of a compressive material such as SiO₂, and stress-relieving material 120 is a tensile material such as Si₃N₄.

In some embodiment, stress-relieving material 120 is silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof. In some embodiment, stress-relieving material 120 is Si_(x)O_(y), and x:y is in a range from about 0.1 to about 10. In some embodiment, stress-relieving material 120 is Si_(x)N_(y), and x:y is in a range from about 0.1 to about 10. In some embodiment, stress-relieving material 120 is Si_(x)O_(y)N_(z), and x:y is in a range from about 0.1 to about 10, or y:z is in a range from about 0.1 to about 10, or x:z is in a range from about 0.1 to about 10. X, y, and z may be adjusted to control the property of stress-relieving material 120.

Stress-relieving material 120 may be formed or deposited by chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), high density plasma CVD (HDPCVD), metal organic CVD (MOCVD), plasma enhanced CVD (PECVD), or other applicable deposition processes.

After stress-relieving material 120 fills or is deposited in stress-reducing structure trench 118, excess portion of stress-relieving material 120 is removed to expose a top surface of dielectric layer 110, as shown in FIG. 1E in accordance with some embodiments. The excess portion of stress-relieving material 120 may be removed by a chemical mechanical polishing (CMP) process.

A stress-reducing structure 122 includes stress-reducing structure trench 118. The shape of stress-reducing structure 122 may be similar to or the same as the shape of opening 114 of first photoresist layer 113. Although it is not shown in the cross-section representation illustrated in FIG. 1E, in some embodiments, stress-reducing structure 122 has a shape that is an enclosed or non-enclosed circle, rectangle, ellipse, square, or polygon, when viewed from a top view or above. In some embodiments, stress-reducing structure 122 includes an n-shaped structure, T-shaped structure, bar-shaped structure, and/or a linear structure. It should be noted that stress-reducing structure 122 may include a plurality of portions having the same or different shapes, and some of the portions may intersect with each other, while some of the portions may not intersect with each other.

In some embodiments, stress-reducing structure 122 has a height H₁ in a range from about 0.09 μm to about 35 μm. In some embodiments, stress-reducing structure 122 has a thickness T₁ in a range from about 0.09 μm to about 3 μm.

In addition, as shown in FIG. 1E, a portion 124 of dielectric layer 110 is surrounded by stress-reducing structure 122 in accordance with some embodiments. Stress-reducing structure 122 is configured to prevent the stress caused or created by dielectric layer 110 from directly entering or acting on portion 124. Therefore, features formed in portion 124 of dielectric layer 110 are protected by stress-reducing structure 122. In some embodiments, portion 124 of dielectric layer 110 has a width W₁ in a range from about 0.01 μm to about 50 μm.

After stress-reducing structure 122 is formed, conductive feature 108 is formed in portion 124 of dielectric layer 110 surrounded by stress-reducing structure 122 in accordance with some embodiments. As shown in FIG. 1F, a second photoresist layer 126 is formed over dielectric layer 110 in accordance with some embodiments. Second photoresist layer 126 includes openings 128 over portion 124 of dielectric layer 110. It should be noted that although three openings 128 are illustrated in FIG. 1F, the number of openings 128 in second photoresist layer 126 is not intended to be limiting. For example, second photoresist layer 126 may only include one opening.

Next, an etching process 130 is performed through openings 128, and via holes 132 are formed in portion 124 of dielectric layer 110, as shown in FIG. 1G in accordance with some embodiments. Second photoresist layer 126 is removed after via holes 132 are formed, as shown in FIG. 1H in accordance with some embodiments.

After second photoresist layer 126 is removed, a third photoresist layer 134 is formed over substrate 102 to cover dielectric layer 110 and stress-reducing structure 122, as shown in FIG. 1I in accordance with some embodiments. In addition, portions 136 of third photoresist layer 134 fill in via holes 132.

Next, an opening 138 is formed in third photoresist layer 134, as shown in FIG. 1J in accordance with some embodiments. Opening 138 exposes portions 136 of third photoresist layer 134 formed in via holes 132 and some portions of dielectric layer surrounded (e.g. enclosed) by stress-reducing structure 122. In some embodiments, opening 138 is formed by an exposure process and a developing process.

After opening 138 of third photoresist layer 134 is formed, an etching process 140 is performed through opening 138 to form a trench 140, as shown in FIG. 1K in accordance with some embodiments. More specifically, top portions of portion 136 formed in via holes 132 and top portions of dielectric layer 110 exposed by opening 138 are removed.

After trench 140 is formed, remaining portions of third photoresist layer 134, including those in via holes 132, are removed, as shown in FIG. 1L in accordance with some embodiments. As shown in FIG. 1L, trench 140 is formed over via holes 132 and is directly connected with via holes 132.

Next, a conductive material 142 is formed over substrate 102 to fill in trench 140 and via holes 132, as shown in FIG. 1M in accordance with some embodiments. Conductive material 142 may be a highly-conductive metal, low-resistive metal, elemental metal, transition metal, or the like. Examples of conductive material 142 may include, but are not limited to, copper (Cu), aluminum (Al), tungsten (W), titanium (Ti), gold (Au), or tantalum (Ta).

After conductive material 142 is formed, a CMP process is performed to form conductive feature 108, as shown in FIG. 1N in accordance with some embodiments. In some embodiments, the top surface of stress-reducing structure 122 is substantially level with the top surface of conductive feature 108. In some embodiments, the top surface of stress-reducing structure 122 is substantially level with the top surface of the conductive feature, and the bottom surface of stress-reducing structure 122 is substantially level with the bottom surface of the conductive feature.

As shown in FIG. 1N, conductive feature 108, including vias 144 and a metal line 146, is formed in portion 124 of dielectric layer 110. Metal line 146 is formed in trench 140, and vias 144 in direct contact with metal line 146 are formed in via holes 132.

In some embodiments, conductive feature 108 has a width W₂ in a range from about 0.01 μm to about 50 μm. Since conductive feature 108 is formed in portion 124 surrounded by stress-reducing structure 122, width W₂ is less than width W₁.

FIG. 2 illustrates a top view representation of semiconductor device structure 100 in accordance with some embodiments. Conductive feature 108 is formed portion 124 of dielectric layer 110 surrounded (or enclosed) by stress-reducing structure 122. As shown in FIG. 2, stress 112 is caused by dielectric layer 110 surrounding conductive feature 108. In addition, stress 112 may be in a direction toward or away from conductive feature 108.

More specifically, stress 112 may be a compressive stress or a tensile stress and may be directed toward or imparted on conductive feature 108. Therefore, if a conductive feature is not surrounded, or protected, by stress-reducing structure 122, the stress may induce or impart undesired forces on conductive feature 108. In addition, the forces may result in a change of electron mobility of the device formed in device region 106 under conductive feature 108. Therefore, the device formed under conductive feature 108 may have poor current uniformity due to stress 112 and the performance of the device may be affected.

Accordingly, conductive feature 108 is formed in portion 124 of dielectric layer 110 surrounded by stress-reducing structure 122, such that stress 112 cannot reach or do not affect conductive feature 108, as shown in FIG. 2 in accordance with some embodiments.

In some embodiments, stress-reducing structure 122 shown in a top view has the shape of a rectangle (but is not limited thereto). In some embodiments, stress-reducing structure 122 has a width W₃, and a ratio of the width W₃ to width W₂ is in a range from about 0.01 to about 2.

It should be noted that although embodiments described above, including embodiments illustrated in FIGS. 1A-1N and FIG. 2, show only one conductive feature formed in one dielectric layer, the semiconductor device structures may include various conductive features in various dielectric layers. That is, the shapes, sizes, and materials of the conductive features may be adjusted depending on their applications, and the scope of the disclosure is not intended to be limiting.

In addition, conductive feature 108 may further include a liner and/or a barrier layer. For example, a liner (not shown) may be formed in trench 140 and via holes 132, and the liner covers the sidewalls and bottom of trench 140 and via holes 132. The liner may be either tetraethylorthosilicate (TEOS) or silicon nitride, although any other applicable dielectric may alternatively be used. The liner may be formed using a plasma enhanced chemical vapor deposition (PECVD) process, although other applicable processes, such as physical vapor deposition or a thermal process, may alternatively be used. The barrier layer (not shown) may be formed over the liner (if present) and may cover the sidewalls and bottom of the opening. The barrier layer may be formed using a process such as chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced CVD (PECVD), plasma enhanced physical vapor deposition (PEPVD), atomic layer deposition (ALD), or any other applicable deposition processes. The barrier layer may be made of tantalum nitride, although other materials, such as tantalum, titanium, titanium nitride, or the like may, also be used.

FIG. 3A illustrates a cross-sectional representation of a semiconductor device structure 100 a in accordance with some embodiments. A interconnection structure 104 a formed in semiconductor device structure 100 a includes conductive features, such as conductive features 108 a, 108 b, and 108 c. These conductive features are formed in a number of dielectric layers, such as dielectric layers 110 a, 110 b, and 110 c. In addition, conductive feature 108 a is surrounded by a stress-reducing structure 122 a formed in dielectric layer 110 a.

Moreover, device region 106 formed in substrate 102 includes a gate structure 401 embedded in an interlayer dielectric (ILD) layer 403, source/drain regions 405, and isolation structures 407. Since stress-reducing structure 122 is formed to protect conductive feature 108 a from stress 112, performance of gate structure 401 can be unaffected although conductive feature 108 a is formed over gate structure 401.

In some embodiments, gate structure 401 includes a gate dielectric layer 409, a gate electrode 411, and spacers (not shown). In some embodiments, gate dielectric layer 409 is made of high k dielectric materials, such as metal oxides, metal nitrides, metal silicates, transition metaloxides, transition metalnitrides, transition metalsilicates, oxynitrides of metals, or metal aluminates. Examples of the dielectric material may include, but are not limited to, hafnium oxide (HfO₂), hafnium silicon oxide (HfSiO), hafnium silicon oxynitride (HfSiON), hafnium tantalum oxide (HfTaO), hafnium titanium oxide (HfTiO), hafnium zirconium oxide (HfZrO), zirconium silicate, zirconium aluminate, silicon oxide, silicon nitride, silicon oxynitride, zirconium oxide, titanium oxide, aluminum oxide, or hafnium dioxide-alumina (HfO₂—Al₂O₃) alloy.

In some embodiments, gate electrode 411 is made of a conductive material, such as aluminum, copper, tungsten, titanium, tantulum, titanium nitride, tantalum nitride, nickel silicide, cobalt silicide, TaC, TaSiN, TaCN, TiAl, TiAlN, or other applicable materials.

ILD layer 403 may include multilayers made of multiple dielectric materials, such as silicon oxide, silicon nitride, silicon oxynitride, tetraethoxysilane(TEOS), phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), low-k dielectric material, and/or other applicable dielectric materials. Examples of low-k dielectric materials may include, but are not limited to, fluorinated silica glass (FSG), carbon doped silicon oxide, amorphous fluorinated carbon, parylene, bis-benzocyclobutenes (BCB), or polyimide. ILD layer 403 may be formed by chemical vapor deposition (CVD), physical vapor deposition, (PVD), atomic layer deposition (ALD), spin-on coating, or other applicable processes.

It should be noted that device region 106 shown in FIG. 3A is merely an example, and other devices may be additionally or alternatively formed in device region 106. In addition, some dielectric layers and conductive features are omitted in FIG. 3A for clarity.

FIG. 3B illustrates a cross-sectional representation of a semiconductor device structure 100 b in accordance with some embodiments. Semiconductor device structure 100 b is similar to semiconductor device structure 100 a except stress-reducing structure 122 b and 122 c are also formed. More specifically, stress-reducing structure 122 b is formed in a dielectric layer 110 b to protect conductive feature 108 b, and stress-reducing structure 122 c is formed in a dielectric layer 110 c to protect conductive feature 108 c.

FIG. 3C illustrates a cross-sectional representation of a semiconductor device structure 100 c in accordance with some embodiments. Semiconductor device structure 100 c also includes gate structure 401 formed in device region 106 of substrate 102, similar to that of semiconductor device structure 100 a or 100 b.

In addition, conductive features 108 a′ and 108 a″ are formed in dielectric layer 110 a in accordance with some embodiments. Conductive feature 108 a′ is surrounded by a stress-reducing structure 122 a′, and conductive feature 108 a″ is surrounded by a stress-reducing structure 122 a″. As shown in FIG. 3C, conductive feature 108 a′ includes one metal line 146 a′ and one via 144 a′ connected with metal line 146 a′. In addition, conductive feature 108 a″ includes one metal line 146 a″ and one via 144 a″ connected with metal line 146 a″. Moreover, in some embodiments, the edges of conductive feature 108 a″ are in direct contact with stress-reducing structure 122 a″, as shown in FIG. 3C in accordance with some embodiments.

Furthermore, conductive features 108 b′ and 108 b″ are formed in dielectric layer 110 b, and conductive feature 108 c′ is formed in dielectric layer 110 c in accordance with some embodiments. As shown in FIG. 3C, conductive features 108 b′ and 108 b″ are both formed in portion 124 which is surrounded by a stress-reducing structure 122 b′. Therefore, conductive features 108 b′ and 108 b″ are both protected by stress-reducing structure 122 b′. Conductive feature 108 c′ includes one metal line 146 c′ and two vias 144 c′ connected with metal line 146 c′ and is protected by stress-reducing structure 122 c′.

As shown in FIG. 3C, conductive features, such as conductive features 108 a′, 108 a″, 108 b′, 108 b″, and 108 c′, with different shapes and sizes can be formed in interconnect structure 104 c. Accordingly, the application of stress-reducing structure, such as stress-reducing structure 122 a′, 122 a″, 122 b′, and 122 c, may also be varied, and the scope of the disclosure is not intended to be limiting.

As described previously, when a conductive feature is unprotected, stress caused by dielectric layer surrounding the conductive feature will induce or impart undesired forces, such as pulling forces, on the conductive feature and will affect the performance of devices formed under conductive feature 108. For example, the electron mobility of the devices may be altered and the devices may have poor current uniformity. Therefore, in various embodiments, the stress-reducing structure, such as stress-reducing structure 122, is formed to protect the conductive features, such as conductive feature 108. As shown in FIG. 1N, conductive feature 108 is formed in portion 124 of dielectric layer 110. Accordingly, conductive feature 108 is surrounded, and protected, by stress-reducing structure 122, and the performance of the devices formed in device region 106 under conductive feature 108 is not affected by stress 112.

Embodiments of mechanisms for a semiconductor device structure are provided. The semiconductor device structure includes a conductive feature formed in a dielectric layer. In addition, the conductive feature is surrounded by a stress-reducing structure (e.g. a guard ring) formed in the dielectric layer. The stress-reducing structure is configured to protect the conductive feature from the stress forces caused by the dielectric layer outside the stress-reducing structure. Therefore, the performance of the devices formed below the conductive feature will not be affected by the stress forces.

In some embodiments, a semiconductor structure is provided. The semiconductor structure includes a substrate and an interconnection structure formed over the substrate. The interconnection structure includes a first dielectric layer and a first stress-reducing structure formed in the first dielectric layer. The interconnection structure further includes a first conductive feature formed in the first dielectric layer, and the first conductive feature is surrounded by the first stress-reducing structure.

In some embodiments, a semiconductor structure is provided. The semiconductor structure includes a first dielectric layer formed over a substrate and a first stress-reducing structure formed in the first dielectric layer. The semiconductor structure further includes a first conductive feature formed in a portion of the first dielectric layer surrounded by the first stress-reducing structure. In addition, the first dielectric layer is made of a compressive material and the stress-reducing structure is made of a tensile material or wherein the first dielectric layer is made of a compressive material and the stress-reducing structure is made of a tensile material.

In some embodiments, a method for forming a semiconductor structure is provided. The method includes forming a dielectric layer over a substrate and forming a trench in the dielectric layer. The method further includes forming a stress-reducing structure in the trench and forming a conductive feature in the dielectric layer. In addition, the conductive feature is surrounded by the stress-reducing structure.

Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. For example, it will be readily understood by those skilled in the art that many of the features, functions, processes, and materials described herein may be varied while remaining within the scope of the present disclosure. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

What is claimed is:
 1. A semiconductor structure, comprising: a substrate; an interconnection structure formed over the substrate, wherein the interconnection structure comprises: a first dielectric layer; a first stress-reducing structure formed in the first dielectric layer; and a first conductive feature formed in the first dielectric layer, wherein the first conductive feature is surrounded by the first stress-reducing structure.
 2. The semiconductor structure as claimed in claim 1, wherein the stress-reducing structure has a shape that is an enclosed or non-enclosed circle, rectangle, ellipse, square, or polygon.
 3. The semiconductor structure as claimed in claim 1, wherein the first dielectric layer is made of a compressive material, and the first stress-reducing structure is made of a tensile material.
 4. The semiconductor structure as claimed in claim 1, wherein the first dielectric layer is made of a tensile material, and the first stress-reducing structure is made of a compressive material.
 5. The semiconductor structure as claimed in claim 1, wherein the first stress-reducing structure is made of silicon oxide, silicon nitride, or silicon oxynitride.
 6. The semiconductor structure as claimed in claim 1, further comprising: a device region formed in the substrate, wherein the first conductive feature is formed over the device region.
 7. The semiconductor structure as claimed in claim 6, wherein the device region includes a gate structure.
 8. The semiconductor structure as claimed in claim 1, further comprising: a second dielectric layer formed over the first dielectric layer; a second stress-reducing structure formed in the second dielectric layer; and a second conductive feature formed in the second dielectric layer, wherein the second conductive feature is surrounded by the second stress-reducing structure.
 9. The semiconductor device structure as claimed in claim 1, wherein a top surface of the first stress-reducing structure is substantially level with a top surface of the first conductive feature, and a bottom surface of the first stress-reducing structure is substantially level with a bottom surface of the first conductive feature.
 10. A semiconductor structure, comprising: a first dielectric layer formed over a substrate; a first stress-reducing structure formed in the first dielectric layer; and a first conductive feature formed in a portion of the first dielectric layer surrounded by the first stress-reducing structure, wherein the first dielectric layer is made of a compressive material and the stress-reducing structure is made of a tensile material or wherein the first dielectric layer is made of a compressive material and the stress-reducing structure is made of a tensile material.
 11. The semiconductor structure as claimed in claim 10, wherein the first stress-reducing structure has a shape that is an enclosed or non-enclosed circle, rectangle, ellipse, square, or polygon.
 12. The semiconductor structure as claimed in claim 10, further comprising: a second stress-reducing structure formed in the first dielectric layer; and a second conductive feature formed in a portion of the first dielectric layer surrounded by the second stress-reducing structure.
 13. The semiconductor structure as claimed in claim 10, further comprising: a second dielectric layer formed over the first dielectric layer; a third stress-reducing structure formed in the second dielectric layer; and a third conductive feature formed in a portion of the second dielectric layer surrounded by the third stress-reducing structure.
 14. The semiconductor structure as claimed in claim 10, wherein the first conductive feature comprises a metal line and a via connected to the metal line, and a top surface of the first stress-reducing structure is substantially level with a top surface of the metal line and a bottom surface of the first stress-reducing structure is substantially level with a bottom surface of the via.
 15. A method for forming a semiconductor structure, comprising: forming a dielectric layer over a substrate; forming a trench in the dielectric layer; forming a stress-reducing structure in the trench; and forming a conductive feature in the dielectric layer, wherein the conductive feature is surrounded by the stress-reducing structure.
 16. The method for forming the semiconductor device structure as claimed in claim 15, wherein forming the stress-reducing structure in the trench further comprises: depositing a stress-relieving material in the trench and over the dielectric layer; and removing a portion of the stress-relieving material to expose a top portion of the dielectric layer.
 17. The method for forming the semiconductor structure as claimed in claim 15, wherein the stress-reducing structure trench has a shape that is an enclosed or non-enclosed circle, rectangle, ellipse, square, or polygon.
 18. The method for forming the semiconductor structure as claimed in claim 15, wherein forming the conductive feature further comprises: forming a via hole in the dielectric layer, wherein the via hole is surrounded by the stress-reducing structure; forming a trench in the dielectric layer, wherein the trench is connected to the via hole; and depositing a conductive material in the via hole and in the trench to form the conductive feature.
 19. The method for forming the semiconductor structure as claimed in claim 18, further comprising: performing a polishing process to remove a portion of the conducive material, such that a top surface of the stress-reducing structure is substantially level with a top surface of the conductive feature.
 20. The method for forming the semiconductor structure as claimed in claim 15, wherein the dielectric layer is made of a compressive material and the stress-reducing structure is made of a tensile material or wherein the dielectric layer is made of a compressive material and the stress-reducing structure is made of a tensile material. 